First-Principle Computed Structural and Thermodynamic Properties of Cu2ZnSn(SxSe1−x)4 Pentanary Solid Solution

This paper is dedicated to the ab initio study of the structural and thermodynamic properties of Cu2ZnSn(SxSe1−x)4 bulk alloys. The calculations are conducted using full-potential linear-augmented-plane-wave plus local-orbital (FP-LAPW + lo) method within the revised generalized gradient approximation of Perdew–Burke–Ernzerhof (GGAPBEsol). This method is used to find more valuable equilibrium structural parameters than the simplest approximations of PBE and local density approximation (LDA). The obtained structural properties appear to be affected by the relaxation effect, and all alloys are thermodynamically favorable to the process according to the enthalpy of formation calculations. We find here a nonlinear dependence of lattice parameters a and c with respectively a small downward bowing parameter b of + 0.09 Å and + 0.19 Å for relaxed structures. The thermodynamic quantities, namely the entropy, the constant volume, the pressure heat capacity (Cv and Cp) and Debye temperature, are computed for different S/(S + Se) atomic ratios by varying temperature from 0 K to 1000 K. These quantities are successfully obtained by using the combined approach of FP-LAPW and a quasi-harmonic model. Overall, there is good agreement between our calculated quantities and other results.